While many Taiwanese trace their ancestry to mainland China and share cultural similarities, most do not want to be ruled by Beijing.

Beijing has long sought to win over Taiwan, where defeated Nationalist forces fled in 1949 at the end of the Chinese civil war. Cut-price summer programmes for young Taiwanese, find-your-roots tours and other schemes push the message that Taiwan would be better off under Beijing and has nothing to fear.

With normal travel links suspended, Beijing has turned to the internet to continue this campaign.

In June, dozens of Taiwanese families joined a gala in the southern mainland city of Fuzhou via video call to celebrate the traditional Dragon Boat Festival.

Mainland state media described the event as an effort to boost “ancestral identity of Taiwan youth” and “express wishes for everlasting love across the Taiwan Strait”.

A video-making contest to “break down barriers created by the virus” is now being advertised to Taiwanese high school students.

“The epidemic has cut off the mountains from the seas, but cannot cut off the longing for home,” an online poster on the competition wrote, which was co-hosted by a Chinese Communist Party youth group based in Fujian province, on the other side of the strait from Taiwan.

The moves have unnerved security agencies in Taiwan.

One agency described them as part of a “new campaign model” to guide political ideology and sow discord towards Taiwan’s government, according to an internal security report reviewed by Reuters.

A second internal security report reviewed by Reuters said the move online made it harder for Taiwanese authorities to trace who was involved and could bring a “new national security crisis”.

“They have been instructed to expand efforts for live broadcasts and video conferences,” a Taiwanese security official investigating the matter said. “They want to increase the favourable impression towards China.”

Security officials say the virtual campaigns are initiated by mainland state agencies including the Taiwan Affairs Office (TAO) and the United Front Work Department, which is in charge of co-opting overseas Chinese and non-communists.

A TikTok spokeswoman declined to comment. Facebook, which owns Instagram, did not respond to requests for comment.

The TAO said in a statement that amid the pandemic it was a “natural choice” to engage with Taiwan’s people online.

But Taiwan’s government was seeking to “stigmatise normal exchanges between compatriots across the strait”, the office said, labelling it a “despicable” move aimed at Taiwan’s independence.

Taiwan’s policymaking Mainland Affairs Council said people needed to stay cautious to avoid “falling into the Chinese Communist Party’s trap” as China’s campaigning “takes a new form”.

But the move might not be as effective as physical exchanges, which China was likely to restart once travel resumed, security officials said.

“It’s harder to convince people without actually seeing what’s on offer,” a second security official said.

Some evidence suggests the campaign is not succeeding.

About 27 per cent of people on the island support Taiwan’s formal independence, a record high, in contrast to 0.7 per cent who want to join with mainland China, according to a July poll by Taipei’s National Chengchi University. Most of those polled preferred to maintain the status quo.

“They have made a lot of effort with the virtual campaign,” the first official said. “But most people in Taiwan are clear-headed.”